(HealthDay News) -- This flu season continues to be one of the nastiest in years. And it isn't helping that the flu vaccine may be less than 20 percent effective against the season's dominant strain, according to a new Canadian report.

In the meantime, thousands of Americans are clogging hospital ERs or suffering at home, with new statistics from the U.S. Centers for Disease Control and Prevention showing cases at epidemic levels.

As of Jan. 27, 48 states (down from 49 last week) continue to experience widespread flu activity, the CDC said, with the more virulent H3N2 strain accounting for most reported flu cases.

Not surprisingly, flu-linked hospitalization rates continued to rise -- from 41.9 per 100,000 people the week ending Jan. 20 to 51.4 per 100,000 people for the week ending Jan. 27.

"As of this week, overall hospitalizations are now the highest we've seen, even higher than 2014-15, our previous high season," said CDC Acting Director Dr. Anne Schuchat during a Friday news briefing.

"We also continue to hear reports of crowded hospitals and spot shortages of antiviral medications and rapid influenza tests," she said. "Unfortunately, our latest tracking data indicate that flu activity is still high and widespread across most of the nation, and increasing overall.

"This week, we are reporting an additional 16 flu-related pediatric deaths for this season, meaning there are even more families now devastated by flu," she added.

The CDC says 53 children have died of the flu so far this season.

Preventing flu with vaccination is the best means of avoiding these tragedies, of course, but statistics released Thursday out of Canada suggest this season's vaccine is just 17 percent effective against the H3N2 strain.

U.S. estimates of flu shot effectiveness are still to come, but Schuchat wasn't surprised by the Canadian number, since it's been tough to craft a potent vaccine against the H3N2 flu strain.

"A single number doesn't really tell the whole story, but we know that H3N2 vaccine effectiveness is lower, year in and year out," she told reporters. "We expect the effectiveness against the H3N2 strains will be low. That's what they saw in Australia at the end of the season, but we don't have that final number yet."

There is one glimmer of hope: Schuchat said flu activity seems to be easing somewhat in Western states, with Oregon showing a dip in caseloads last week.

Dr. Daniel Jernigan directs the CDC's influenza division. Speaking at the news conference, he agreed that "if this current trend in hospitalization rates is maintained through the season, it is possible the number of flu hospitalizations may well exceed 710,000 as seen in 2014-15."

Older flu patients are still the most prone to needing hospital care, the report showed, as rates continued to be very high for people between the ages of 50 and 64.

But CDC officials stressed that, even if the vaccine's effectiveness is relatively low compared to prior seasons, it's still important -- and not too late -- to get a flu shot.

That's because any protection is better than none, and studies have shown that being inoculated can at least reduce the severity of the flu if you get it.

That's particularly true for kids, Jernigan said.

"For this season, only 20 percent of these pediatric deaths have been vaccinated, and half of these children were otherwise healthy," he noted. And these deaths were associated with H3N2, H1N1 and influenza B strains -- "all of the different types of influenza are causing these deaths," Jernigan said.

Schuchat also stressed that "we are by no means out of the woods. Most seasons last up to 20 weeks, and we've probably got several weeks left of increased flu activity."

Despite the severity of the season, the American Lung Association says there are things you can do to avoid being stricken by the virus.

"The flu is more than just 'a bad cold.' It's a serious respiratory illness that's easily spread from person to person, usually when the person with the flu coughs or sneezes," said Dr. Norman Edelman, senior scientific advisor for the American Lung Association.

"Symptoms of the flu include fever, cough, weakness, aches and pains," Edelman said in a lung association news release. "If you have asthma or other lung diseases, you are at higher risk of developing complications from the flu."

There are a number of ways people can protect themselves and others. They include:

Get a flu shot. Though this year's vaccine isn't a perfect match for the viruses in circulation, it's still the best way to protect against infection. And some protection is better than none. Flu season may not end until May. The flu shot will remain effective for roughly six months.

Seek medical attention. People who develop flu-like symptoms should see a doctor right away. Antiviral medications such as Tamiflu and Relenza can help ease symptoms, but these drugs are most effective if taken within 48 hours of getting sick.

Don't spread the misery. If you get the flu, take steps to prevent passing the infection to others. Sick people should cover their mouth and nose with a tissue when coughing or sneezing. Hands should be washed frequently. People should avoid touching their eyes, nose or mouth, particularly if their hands aren't clean. Be sure to disinfect possibly contaminated surfaces and objects. Anyone with the flu should stay home and not go to work or school for about a week. Once flu symptoms appear, people are contagious for five to seven days.

More information

The U.S. Centers for Disease Control and Prevention has more about the flu.

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